1. Field of the Invention
The present invention relates to a chip device and method for converting a format of a video signal in a digital TV receiver.
2. Discussion of the Related Art
The format converting chip is a device for converting formats of various video signals, such as color space, and chroma formats. In general, there are a variety of video standards, inclusive of digital TV broadcasting, analog TV broadcasting, such as NTSC, PAL, SECAM, and, other digital pictures, such as S-video, and computer video signals, such as VGA, SVGA, and XGA. That is, there are different video standards for different system applications. The video signal standards can be sorted with reference to the following formats.
First, there are spatial resolutions of 720×480, 1280×720, and 1920×1080 pixels depending on system applications. There are frame rates of 24, 30, 59.94, 60, and 80 Hz depending on system applications. There are scanning methods of interlace scanning and progressive scanning depending on system applications. There are screen aspect ratios of 4:3, 16:9, and 14:9 depending on system applications. There are color spaces and gamma corrections of RGB, YCbCr, YUV, and YIQ and the like depending on system applications. Finally, there are chroma formats of 4:2:0, 4:1:1, 4:2:2, and 4:4:4 depending on system applications.
Different from current analog television broadcasting, the digital TV broadcasting supports multi-format of video signal. In general, the format herein denotes four kinds of formats of the spatial resolution, the frame rate, the scanning method, and the aspect ratio. Accordingly, the digital TV receiver can receive a variety of video signals, such as an HD (High Definition) class video signal, an SD (Standard Definition) class video signal, a computer video signal, and an analog TV broadcasting signal, requiring to receive and process various kinds of video signals. That is, the digital TV receiver is expected to have applications to a variety of displays, such as, not only to a Braun tube TV receiver and projection TV receiver, both of the interlace scanning method, but also to LCD (Liquid Crystal Display) and PDP (Plasma Display Panel), both of the progressive scanning method, and computers.
Consequently, the digital TV receiver is required to provide video signals on a variety of formats, and to be provided with a format converting device for converting input video signals on different formats into output video signals on desired formats. Conventionally, conversions of the spatial resolutions, the frame rates, the scanning methods have been in general defined as format conversions. Recently, besides the foregoing format items, methods for adding the aspect ratios thereto are suggested. The format converting device in the digital TV receiver converts input video signals on various formats into output video signals on desired formats, i.e., for an example, the format converting device converts the spatial resolutions, the frame rates, the scanning methods, and the aspect ratios consistent to desired output formats.
FIG. 1 illustrates a block diagram showing a related art format converting device in a digital TV receiver for converting formats of video signals of analog TV broadcastings, and computers.
For an example, when video signals on different formats are received at the digital TV receiver, the format converting part therein converts a format of a received video signal into a video format (for an example, 1920*1080, 60 Hz, and YCbCr) required by the digital TV receiver, and a video signal on the converted format is provided to the digital TV receiver. In other words, upon reception of a digital broadcasting signal, the format converting part 105 analyzes the four kinds of format information contained in a digital bitstream, and carries out an appropriate format conversion by using the analyzed four kinds of format information. On the other hand, because the analog TV broadcasting video signals and the computer video signals contain no format information, the digital TV receiver is in general required to convert formats of the input video signals into 601 formats (i.e., component digital interface standards) the CCIR recommends. Then, the format converting part 105 can convert the format of the input video signal.
For an example, upon reception of an NTSC TV broadcasting composite video signal, an NTSC decoder 101 separates a horizontal synchronizing signal and a vertical synchronizing signal, and a luminance signal ‘Y’ and a color signal ‘C’ therefrom. If necessary, a color converting part 102 makes a color space conversion (for an example, YIQ→YCbCr) and a chroma format conversion (for an example, 4:2:0→4:2:2) of the input video signal, and forwards the result to the format converting part 105. By the way, the VGA and SVGA and the like, computer video signals, are provided to the digital TV receiver through an RGB input part 103 in forms of RGB, when a color converting part 104 makes a color space conversion (for an example, RGB→YCbCr) and a chroma format conversion (for an example, 4:4:4→4:2:2) of the input video signal, and forwards the result to the format converting part 105.
As described, the related art format converting device can not make a direct format conversion of the external video signals, such as the computer video signals and the analog TV broadcasting video signals. As shown in FIG. 1, in order to convert a format of an input video signal, separate color space conversion and chroma format conversion are required according to the kinds of the video signals at a step prior to the related art format converting device. At the end, as individual hardware is required according to the number of input video signals, not only the production cost is high, but also the system is complicated. In other words, every time, an external video signal is added, additional hardware is required for making the chroma format conversion and the color space conversion prior to the format conversion part. Taking the trend of gradual integration of many media into the digital TV receiver into account, it is foreseen that a wider variety of video signals will be provided to the digital TV receiver, to require additional converting parts, other than the format converting part, for the chroma format conversion and the color space conversion, that leads hardware of the digital TV receiver bulky.